Mechanism for simultaneously adjusting the step support angles of a straight staircase

ABSTRACT

A mechanism for simultaneous angle adjustment of support elements ( 4 ), particularly for setting up a mold structure for the steps of a straight staircase, has a casing ( 9 ) in which at least two interdependent shafts ( 6 ) are arranged. Each of the shafts ( 6 ) extends into the next shaft in a nested configuration where the successive intervals between the shafts are adjustable. Each shaft has a threaded portion ( 6   a ) traversing an internally threaded block ( 11 ) that is located in the casing and holds one of the support elements ( 4 ). A shaft ( 12 ), running parallel to the two or more shafts ( 6 ), passes through the blocks and is equipped with eccentrics ( 13 ), where each of the eccentrics ( 13 ) is respectively associated with one of the blocks ( 11 ). The eccentrics are constrained to share the rotation of the shaft ( 12 ), and the eccentric of each block interacts with the respective support element that is associated with that block, so that by pushing against the support element, the eccentric sets the support element to a predetermined slope angle (A).

[0001] The present invention relates to a mechanism for simultaneouslyadjusting step support angles for the purpose of realizing a moldstructure for a straight staircase.

[0002] The mechanism is of the type that includes a casing, inside ofwhich at least two interdependent shafts are arranged in a nestedconfiguration so that each shaft extends into the next shaft, whereinthe successive intervals between the shafts are adjustable, and whereineach shaft has a threaded portion traversing an internally threadedblock that is seated in the casing and holds a stair-step support.

[0003] Until now, the procedures for building mold structures forstraight stairs have remained at the pre-industrial level. One starts bytracing the vertical line of each riser on the sidewalls. Next, stripsof lumber are put in place on the tracing by means of nails or pins, andsubsequently, the molds for the risers are attached to the lumberstrips.

[0004] To make these molds is a time-consuming and therefore expensiveprocess and requires specialized labor, without providing assurance ofthe quality and precision required.

[0005] To improve the technique, the U.S. Pat. No. 2,883,759 proposes astair mold arrangement in which the mold boards are supported by astructure that extends above the staircase that is to be built.

[0006] The boards are held by arms or suspension elements that aremovable and adjustable along the axis of the structure, and thus alongthe axis of the staircase. The arms are guided in two parallel gliderails, and a scissors mechanism allows all of the suspension armscarrying the mold boards to be moved together, whereby the intervalbetween the support arms is automatically adjusted.

[0007] Unfortunately, an arrangement of this kind is very fragile, andthe rapid wear on the scissors joints will lead to an amount of playthat is incompatible with the desired level of precision.

[0008] Furthermore, the members of the scissors are often bentaccidentally, which causes malfunctions that are further aggravated bythe fouling of the mechanism from splashed concrete.

[0009] Moreover, a molding arrangement for a straight staircase isdescribed in DE 1 934 586, which is designed to allow the spacing of thesteps by means of a casing containing a plurality of shafts that areinterdependent and can be nested, where the successive intervals betweenthem can be adjusted. To accomplish this, each shaft has a threadedportion running through a block that is located in the casing.

[0010] With arrangements of this kind, it is not possible to arbitrarilyvary the angles of the supports that determine the position of therisers (these angles vary as a function of the depth of each horizontaltread and of the height of each riser). Thus, these devices do not offerthe possibility to produce any desired step configuration of a straightstaircase, and they are limited by the fact that the height and depth ofthe steps can only be varied together, so that the use of these devicesis limited to certain step configurations.

[0011] The object of the invention is to propose a device which, inaddition to the setting of variable intervals between the shafts, alsoallows a variable setting for the angles of the tread supports, therebymaking it possible to produce all types of staircases by means of thesame device.

[0012] According to the invention, the mechanism for simultaneouslyadjusting the support angles in the step configuration for setting up amold structure for a straight staircase has a shaft that runs parallelto the at least two aforementioned shafts that serve to adjust thespacing. The parallel shaft passes through the blocks and is equippedwith eccentrics, each of which is associated with one of the blocks. Theeccentrics are constrained to share the rotation of the parallel shaft,and each eccentric interacts with a support element that is associatedwith the same block, so that by pushing against the support element, theeccentric sets the support element to a predetermined slope angle.

[0013] A mechanism of this kind is useful for a multitude ofapplications, particularly for configuring the steps of straightstaircases, mechanisms for feed distribution in agriculture, etc.

[0014] According to one characteristic of the invention, the shaftpasses through the entire set of eccentrics and is profiled so that theeccentrics are taken along by a rotation of the shaft and each eccentricwill turn in its respective block, driven by an actuating means that isprovided at one end of the shaft.

[0015] Other features and benefits of the invention will become evidentfrom the following description which refers to a preferred embodimentillustrated in the attached drawings, wherein:

[0016]FIG. 1 schematically illustrates several straight staircases withdifferent slope angles shown in a side view;

[0017]FIG. 2 shows a perspective view of one embodiment of the inventivemechanism for adjusting the angles of the support elements;

[0018]FIG. 3 illustrates a portion of the mechanism of FIG. 2, shownlengthwise in a side view; and

[0019]FIG. 4 gives a perspective view of a portion of the mechanism ofFIG. 2 with a threaded shaft passing through a block for the adjustmentof the variable spacing.

[0020] Three straight staircases 1, 1 a, 1 b are shown in FIG. 1, withtheir respective horizontal treads 2, 2 a, 2 b and their respectiverisers 3, 3 a, 3 b, with the stair strings extending along the planes I,Ia, Ib, respectively. These planes have respective slope gradients A,A1, A2 relative to the horizontal, depending on the height of the risersand the depth of the horizontal treads. Step supports can be arranged onthe stair strings in appropriately inclined positions for setting up amold structure that is known per se and is not shown in the drawing.

[0021] The mechanism illustrated in FIGS. 2 to 4 is designed to allowthe simultaneous adjustment of the angles of the step support elements 4which are known per se and which are designed to rest against thestrings of a straight staircase of the type exemplified by thestaircases 1, 1 a and 1 b in FIG. 1.

[0022] This mechanism includes a casing 9 in which at least twointerconnected shafts 6 are arranged in nested engagement, spaced atadjustable intervals. This arrangement is known per se and thereforedoes not need to be described in detail. It is of the kind described inthe German utility model 19 34 586.

[0023] Each shaft 6 has a threaded portion 6 a passing through a block11 that is held captive in the casing 9 and carries a step supportelement 4. The mechanism has a shaft 12 that runs parallel to the atleast two aforementioned shafts 6. The shaft 12 passes through theblocks and is equipped with eccentrics 13, each of which is associatedwith one of the blocks 11. The eccentrics 13 are constrained on theshaft 12 to share the rotation of the shaft, and each eccentricinteracts with the step support element 4 that is associated with thesame block 11, so that by pushing against a cam-follower head 14 of thesupport element 4, the eccentric sets the support element 4 to apredetermined slope angle A, A1, A2, which represents the angle of thestaircase to be built.

[0024] The shaft 12 passes through all of the eccentrics 13 and isprofiled so that the eccentrics 13 are taken along by a rotation of theshaft 12 and each eccentric 13 will turn in its respective block 11,driven by an actuating means 15 that is provided at one end of the shaft12, for example a hand crank.

[0025] Each support element 4 is pivotally joined to its respectiveblock 11 by a transverse axle pin 16 to allow an angular swivel movementof the support element 4 in the longitudinal direction.

[0026] The bottom wall of the casing 9 has a lengthwise slot 17 throughwhich the adjustable step support elements 4 protrude to the outside.The slot 17 is closed off by a seal 18 with elastic lips to providepassage openings (not visible in the drawing) for the support elements.

[0027] The mechanism according to the invention offers an advantageousway of adjusting the variable distance intervals between the shafts 6and of adjusting the angles A, A1, A2 of the support elements 4 thatdetermine the position of the risers.

[0028] The casing 9 can be fixed on a wall plate (not shown in thedrawing) which defines the beginning of the stair steps, andsimultaneously on another wall plate that defines the end of the stairsteps. The wall plates are configured to hold the base of one casing andon the other hand to hold a second casing at any place within itslength.

[0029] The invention has numerous other uses besides making the steps ofstraight staircases, and it is amenable to diverse variations in itsreduction to practice.

1. A mechanism for simultaneous angle adjustment of support elementsrelating to stair steps, said mechanism being part of a mold structurefor a straight staircase and comprising a casing in which at least twointerdependent shafts are arranged, each extending into the next of saidinterdependent shafts in a nested configuration where the successiveintervals between the interdependent shafts are adjustable, and whereineach of said interdependent shafts has a threaded portion traversing aninternally threaded block that is located in the casing and holds one ofthe support elements, said mechanism further comprising a rotatableshaft running parallel to said at least two interdependent shafts, saidrotatable shaft passing through the blocks and being equipped witheccentrics, each of said eccentrics being respectively associated withone of the blocks, said eccentrics being constrained to share a rotationof said rotatable shaft, wherein the eccentric of each block interactswith the support element that is associated with said block, so that bypushing against the support element, the eccentric sets the supportelement to a predetermined slope angle (A).
 2. The mechanism accordingto claim 1, wherein the rotatable shaft passes through all of theeccentrics and is profiled so that the eccentrics are taken along by therotation of the shaft and each eccentric will turn in its respectiveblock, driven by an actuating means that is provided at one end of therotatable shaft.
 3. The mechanism according to claim 1, wherein eachsupport element is pivotally joined to its respective block by atransverse axle pin to allow an angular swivel movement of the supportelement in the longitudinal direction.
 4. The mechanism according toclaim 1, wherein each of said eccentrics interacts with a cam-followerhead of the support element, so that by pushing against the cam-followerhead, the eccentric sets the support element to a predetermined slopeangle.
 5. The mechanism according to claim 1, wherein the casing has alengthwise slot through which the adjustable support elements protrudeto the outside, wherein the slot is closed off by a seal with elasticlips to provide passage openings for said support elements.